1. Field of the Invention
The present invention relates to an apparatus and method for transferring data between a source and a plurality of receiving data processing devices. More particularly, this invention relates to assigning a unique address for each data processing and peripheral device in a local area network in order to transfer data between each of those devices.
2. Background Information
In the computing industry, it is quite common to transfer data and commands between a plurality of data processing devices, such as computers, printers, displays, terminals, and other network resources. Interconnection of computers and other peripheral devices principally developed in the early 1970s with the advent of computer networking systems which permitted the distribution of access to computing resources beyond the immediate proximity of a mainframe computer.
Recently, "local area networks" (LANs) have been developed which allow transfer of data between a localized set of computing and peripheral devices, typically in the same geographical area such as one building or a plurality of buildings closely situated together. Examples of such LANs may be found in U.S. Pat. Nos. 4,063,220, 4,661,902 and 4,689,786. In the AppleTalk.RTM. (a trademark of Apple Computer, Inc.) network system, each "node" or computer, printer, peripheral, and other network resource, previously had a unique 8 bit identifier which allowed the node to filter out transmissions directed to other nodes. Since the 8 bit identifier, or node ID, was 8 bits in length, the number of nodes or computers and peripherals and other network resources in the LAN was limited to 254 (this number is less the values where all the bits are set and all of the bits are clear, which are reserved). This has resulted in a limitation in the utility of such LANs, since an expansion beyond the 254 node limit required the connection of additional hardware to the system, such as network routers and/or other hardware devices. This resulted in an increase of the complexity of the local area network, as well as an increase in its cost.
As will be described, the present invention provides a local area network for communication and resource sharing among various computers, servers, disks, printers, modems, and other data processing devices, peripherals and network resources, which increases the current 254 node limit to nearly 2.sup.24 or approximately 16 million nodes while remaining compatible with earlier non-extended local area networks which may still be connected to it through network routers. Specifically, this invention relates to an assigning of a unique node address to a node during node power-up or restart in such a way that previous network applications and devices continue to work without modification.